This invention relates to power tools having a rotating shaft and, more particularly, to a shaft lock arrangement for such a tool.
In a power tool such as a router, an internal motor has a rotating shaft coupled to receive a cutting tool at an exposed end. Cutting tools of varying characteristics are selectively installed on, or removed from, the shaft, depending upon the job being performed by the operator of the router. For installation and removal of a cutting tool, the shaft must be locked against rotation. If power is supplied to the motor while the shaft is locked, this can result in damage to the motor. It is therefore an object of the present invention to provide an arrangement for locking the shaft of a power tool and automatically preventing power from being supplied to the motor when the shaft is locked.
If the power tool is connected to a source of power by means of a line cord when the shaft is locked for installation, removal or replacement of a cutting tool, it is possible that even with a power cut-off arrangement as described above, when the shaft is unlocked, power could be supplied to the motor, thereby resulting in unintended rotation of the shaft. It is therefore desirable that the operator disconnect the power tool from the power source when the shaft is to be locked. Accordingly, it is a further object of this invention to provide an arrangement which indicates to the operator that the power tool is connected to a source of power when the shaft is locked.